This is core to their argument, but it's false. Looking at the mean income of the lowest quintile in the US, historical and adjusting for inflation:
1980 $4,310 $13,757 1990 $7,166 $14,420 2000 $10,190 $15,563 2010 $10,994 $13,260 2018 $13,995 $14,658
(And, of course, internationally income has improved dramatically)
This is core to their argument, but it's false. Looking at the mean income of the lowest quintile in the US, historical and adjusting for inflation:
https://www.taxpolicycenter.org/statistics/household-income-...(And, of course, internationally income has improved dramatically)